WASHINGTON — Immediately after President Trump unveiled his controversial trade tariffs Thursday, one Republican senator urged Congress to overturn them and another GOP lawmaker blasted the move as a tax hike.

"I will immediately draft and introduce legislation to nullify these tariffs, and I urge my colleagues to pass it before this exercise in protectionism inflicts any more damage on the economy," Sen. Jeff Flake of Arizona tweeted.

I will immediately draft and introduce legislation to nullify these tariffs, and I urge my colleagues to pass it before this exercise in protectionism inflicts any more damage on the economy. https://t.co/Js9TNzPRBc

Sen. Orrin Hatch, R-Utah, chairman of the Senate Finance Committee, said Trump's action would hurt American businesses and families. “Simply put: This is a tax hike on American manufacturers, workers and consumers,” Hatch said.

Trump signed a 25% tariff on steel imports and 10% on aluminum imports at the White House on Thursday, saying it would revive those industries hurt by unfair trade practices in the global marketplace. The president said some U.S. allies, such as Canada and Mexico, will be exempt as they work with the U.S. to renegotiate the North American Free Trade Agreement.

But those exemptions brought little comfort to concerned Republicans in Congress.

"I don’t think our trade policy ought to be used as a playing card in the talks with both Canada and Mexico on NAFTA," said Sen. Pat Roberts, R-Kansas, before the announcement. "He's exempting our allies, but it’s sort of a pick-and-choose thing. There’s no real stability or predictability."

Flake said even with the exemptions, the tariffs would cause "tremendous damage" to America's diplomatic relationships across the world.

Many Republicans fear Trump's decision will spark a trade war and damage the U.S. economy just eight months before the 2018 elections. House Speaker Paul Ryan, R-Wis., and other GOP leaders had spent the last few days furiously lobbying Trump to scale back the tariffs, an effort that had limited effect.

"I disagree with this action and fear its unintended consequences," Ryan said in a statement Thursday afternoon. He said he was glad Trump included an exemption for Canada and Mexico but said he would press the White House for more changes.

"We will continue to urge the administration to narrow this policy so that it is focused only on those countries and practices that violate trade law," Ryan said.

Before Trump's announcement, Flake said he believed "a number of people" would draft legislation to nullify the tariffs.

Senate Majority Leader Mitch McConnell, R-Ky., did not offer any hints about whether he would support a move to overturn the tariffs through legislation.

In a statement, McConnell said he was "concerned about the scope" of the tariffs and their impact on the U.S. economy. "Important questions remain about whether ultimately these tariffs will be sufficiently targeted, tailored and limited," McConnell said.

GOP Sen. Ron Johnson of Wisconsin said he is considering backing legislation to require congressional approval for such trade actions. Sen. Mike Lee, R-Utah, introduced the legislation in January 2017 as a response to what Republicans said was executive overreach by President Obama.

"Congress in so many areas has ceded power and authority to the president," said Johnson, who chairs the Senate Homeland Security and Governmental Affairs Committee. "We should probably start taking some of that back."

Johnson said he's sending a formal letter to the administration to get a better understanding of their reasoning for Thursday's actions.

"What are their facts?" he asked. "If I have to hold oversight hearings, I'll do that as well."

Asked whether he would back legislation to undo the tariffs, Johnson said: "We'll cross that bridge when we come to it." He questioned whether Democrats would help Republicans block the tariffs.

Will Democrats help?

Sen. Dick Durbin of Illinois, the Senate's No. 2 Democrat, said he wanted to see what Trump produces, but he believes Trump is "painting with too broad a brush."

"I think doing it in a generalized way runs the risk of an all-out trade war, which hurts many of our allies who are not guilty of trade abuses," Durbin said.

The Senate's top Democrat, Charles Schumer of New York, said Trump's instincts on trade were right. But the president was in danger of hurting U.S. allies with his broad approach.

Schumer and others said Trump should focus on the punitive trade levies on China and other global competitors who have flooded the U.S. market with cheap steel and aluminum, undercutting American manufacturers of those products.

"China has been rapacious about trade," Schumer said on the Senate floor Thursday. "If we don't stop China, America will be a weaker place with fewer good-paying jobs, with less wealth, less strength."

But "the haphazard way these tariffs were put together has caused the policy to miss the mark," Schumer said.